1. Field of the Invention
This invention relates to a flattening and take-off apparatus for processing a blown plastic film made by means of a stationary film-blowing head, and more particularly to a flattening and take-off apparatus including a cutter to slit the flattened tubular film along one longitudinal edge, and an unfolding device to turn portions of the cut tubular film to provide a single layer web.
2. Description of the Prior Art
Tubular film flattening and take-off apparatus is known from published German Application No. 33 24 978. In that known apparatus a cutting knife is disposed approximately in the axis of rotation of the apparatus, so that during a reciprocating operation of the apparatus one ply of the tubular film web will be centrally slit. The central slitting of one ply of the tubular film web can, however, have edges of the resulting unfolded film web that are not perfectly parallel to each other.
Further, apparatus disclosed in German Utility Model Specification No. 17 99 446 is used to make a film web from a flattened tubular film wherein the latter is slit at a fold line and is unfolded about the other fold line by a wedge-shaped unfolding device. However, the fold line about which the tubular film is unfolded remains visible in the film web and is undesirable. Further, the unfolding device disclosed in that publication cannot be used in a flattening and take-off apparatus used in conjunction with a tubular film blowing apparatus because the unfolding device cannot be adjusted to adapt to changing operating conditions.
It is an object of the present invention to provide an apparatus in which extruded and flattened tubular film webs can be slit and unfolded to form unfolded film webs that have substantially parallel side edges, and that do not exhibit pinch marks or fold line marks.